For the purpose of medical investigations, a coelioscopy technique is often employed, which consists in pressurising the volume delimited by the peritoneum, ensuring a raising of the abdominal wall, before introducing into the latter a trocar allowing passage of an optical device allowing visualisation of the state of the organs on which investigation is to be carried out.
It is also known to use this technique for carrying out surgical operations. In such a case it is suitable to make passages for several trocars of which some serve for visualising the organs on which the operation is to be carried out, and of which others serve for passage of the instruments.
The raising of the wall is currently obtained by a sufficient pressure difference between the peritoneal cavity and the outside. However this pressure difference cannot be increased without danger because of circulatory or ventilatory disturbances which this could cause.
Now, the plurality of the passageways causes gas leaks which are sufficiently large to prevent keeping a sufficient pressure inside the peritoneum. In fact, pneumoperitoneal insufflation apparatuses have a flow rate which is limited by construction, in particular for safety reasons. Furthermore, the increase of pressure inside the peritoneal cavity represents some danger during the course of a laparoscopy.
This constraint of relative airtightness requires that all the instruments used must be very specifically adapted so as to obtain as complete an airtightness as possible in the crossing of the wall. This extremely rigorous technical constraint is a very restricting factor in the design and production of coelioscopic surgical instruments.
Moreover, the appearance of operating techniques comprising the ablation of tissue volume or of larger organs requires the creation of extraction orifices of greater size than those normally used in conventional laparoscopy. These extraction orifices generate considerable leaks from the pneumoperitoneum which cause collapse of the wall, which is manifested by an almost complete disappearance of the operating volume as well as the zone of visibility for the practitioner.